Teitelbaum, the medical director of the national Fibromyalgia and Fatigue Centers and author of several books on the topic, including “From Fatigued to Fantastic!” also unlawfully used his Facebook account to promote his products for disease treatment and prevention, the FDA said in the three-page letter.

More than a dozen of products on the Teitelbaum’s website endfatigue.com are marketed with therapeutic claims – meaning they can prevent, cure or treat disease -- which classifies them as drugs, the FDA said. But the supplements have not been approved as drugs by the FDA and do not have Generally Recognized As Safe or GRAS status.

The products are also promoted for treating conditions shouldn’t be self diagnosed or treated by non-medical practitioners, the FDA said. As a result, they don’t have adequate directions for use and are considered “misbranded.”

The FDA found the section on Teitelbaum’s website titled “Cures A-Z,” especially problematic because it listed a number of medical conditions with information on how to treat these conditions – along with products offered for sale through the website.

For example, it recommended “Eskimo 3 Fish Oil” as a treatment for Alzheimer’s Disease and claimed the product could “help treat any hidden depression which may be present.”

And in one example of a Facebook post, Teitelbaum wrote that he looked at a new study “showing that an herbal can beat the pants off a pain medication when managing arthritis,” according to the warning letter. In that post, he included a link titled, “Herbal Beats Pain Medication in New Arthritis Study,” which links to his website, endfatigue.com. “The webpage accessible through that link includes the claim described above for your Healthy Knees and Joints product,” the FDA said.

The FDA’s surveillance of false or misleading claims on Facebook is of great interest to the supplement industry. One important lesson for manufacturers is “the continued tendency for the FDA to consider social media as a source for illegal claims, when linked to products for sale,” wrote the Natural Products Insider. “There is no safe haven in Facebook or Twitter.”

In a statement, Teitelbaum characterized himself as a “patient advocate reporting on thousands of scientific studies.” His goal is to “help people become aware of the pros and cons of new research on both natural health products and prescription treatment options.”

Teitelbaum said he recognized the need for the regulations but was “surprised” by FDA’s letter. The “Cures A-Z” section is no longer on the site; Teitelbaum said he is working with the agency to address concerns.

“Current FDA regulations do not allow disease-related claims to be made for natural products, unless the product has gone through the FDA drug approval process, which can cost upward of $500 million, making this impossible for most non-patentable natural options,” he said.

“This often creates a difficult line between what is considered simply reporting on a research study result versus what is considered making a promotional product claim to treat a disease, even if the report is based on solid research.”

Teitelbaum vowed to keep advocating “for consumer access to truthful, reliable, information about the thousands of studies demonstrating the health benefits of natural dietary supplements and herbal products, while ensuring the language on the web site complies with FDA regulations.”

Still, after reading the warning letter, you could almost hear a collective sigh by agency staff. “The unlawful disease treatment and prevention claims made on your website were too numerous to list in this letter,” wrote Evelyn Bonnin, District Director of the FDA’s Baltimore District Office.

The FDA listed the following dietary supplements as being marketed as unapproved drugs but also noted the list was only a fraction of the violations.